Sibby Barrett has a plethora of enticing recipes she can re-create in her eclectic home kitchen any old time. As a baker who founded the Dallas Affaires Cake Company 25 years ago, and the current owner and cooking instructor of Onion Creek Kitchens at Juniper Hills Farm, Barrett moves with great ease and confidence from oven to stove and from sweet to savory.

But when it comes to the tried-and-true dish that epitomizes Barrett as a home chef, it isn’t the expected exotic soufflé or ingredient-intensive entrée that springs to her mind, but rather a vibrant green sauce she learned to craft in early adolescence.

What had begun in the late 1960s as a father’s retreat to an artistic community in San Miguel de Allende, Mexico, turned into an unexpected culinary awakening for his curious 11-year-old daughter. While her science-fiction-writer dad scribbled away, young Barrett was deep in her own study—watching the hardworking 16-year-old housekeeper prepare an array of authentic Mexican dishes for the family. “We had a language barrier,” Barrett says. “But I think cooking was our way of talking and communicating.” The teenager schooled her watchful pupil on such things as sweating onions, cooking garlic, making mole and, best of all, realizing the magic of tomatillo sauce.

The lessons in San Miguel extended beyond the confines of the tiny kitchen. Walking the beaten cobblestone streets of the city with a frozen fruit paleta in hand, Barrett saw vendors selling whole pigs and cows. “They used every piece of everything,” she says. “So it’s kind of ironic that, 40 years later, that’s how people are cooking.” Buying from those vendors and artisans, Barrett cultivated an appreciation for all things handmade and locally produced that she carries into her work to this day.

Two years later, the family left San Miguel, and for many years Barrett found it difficult to recapture the distinct flavors of the city. Tomatillos proved especially difficult to track down and even harder to buy in bulk. But finally, in Barrett’s early twenties, tomatillos made a dramatic and permanent resurgence in her cooking. As a young chef, eager to find any excuse to throw a themed party, Barrett recreated a version of the beloved tomatillo sauce from her youth for a green-themed St. Patrick’s Day party. “People went crazy over it,” she says. “And I remember thinking this is a recipe I need to keep doing.” Now a staple in her cooking, the versatile tomatillo sauce finds its way into enchiladas and stews, and as an accompaniment to fish, chicken and chips.

The many influences of San Miguel are deep and long lasting for Barrett. Colorful kitchen tiles and a heavy molcajete on a corner shelf pay homage to her culinary beginnings, and much of her teaching reflects the lessons she learned while living in the city. And today, when she places handfuls of green tomatillo orbs into her market basket, people often stop and ask, “What are you going to do with those green things?” The answer for Barrett is easy, of course: everything.